This invention relates to pianos and similar stringed musical instruments, and deals more particularly with an improved soundboard assembly for such instrument.
In the past it was believed by many people that the best piano soundboards were made from unlaminated sheets of wood made by gluing or otherwise joining a number of planks or boards edge-to-edge to produce a panel of sufficient size. Such unlaminated wooden soundboards are, however, expensive to make, use material which is becoming very difficult to obtain, and are subject to cracking, warping and other aging problems. To overcome these problems plywood is now often used for soundboards, and various other types of laminated structures have been proposed and used to some degree.
The general object of this invention is to provide a soundboard assembly for a piano or the like using a laminated soundboard, and which assembly is an improvement over previous assemblies using soundboards of plywood or other laminated material.
A further general object of this invention is to provide a soundboard assembly for a piano or the like which assembly has a soundboard using only a relatively small amount of wood and yet which has musical characteristics closely matching or superior to the best performing prior art soundboard assemblies.
A more detailed object of the invention is to provide a soundboard assembly of the foregoing character wherein the soundboard has a relatively small thickness in comparison to the thickness of present soundboards and yet has such modulus of elasticity, areal density, and damping characteristics as to provide the soundboard with a highly desirable frequency response.
A still further detailed object of the invention is to provide a soundboard assembly of the foregoing character including a plurality of ribs secured to the soundboard and also made of a laminated construction which allows the ribs to be made of a substantially smaller dimension than is presently customarily the case.
Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment and from the accompanying drawings.
Prior disclosures which are material to the invention described herein and which are known to the applicants are U.S. Pat. Nos. 222,287; 2,428,325; 2,674,912; 3,427,915; 3,477,330; 3,641,862; 3,664,911; 3,699,836; 3,724,312; and 3,880,040; and British Pat. Nos. 581,954 and 591,268.
In composite material consisting of carbon fibers embedded in a resin matrix the carbon of the fibers is sometimes of an amorphous form and sometimes of a crystalline form, and the fibers are sometimes called by different names such as "carbon fibers," "graphite fibers" or "carbon-graphite fibers" which do not consistently refer to one or the other carbon form. As used herein the term "carbon fiber" is used to refer to all types of fibers made of carbon and to include amorphic and crystalline carbon as the material from which the fibers are made.